Fixing of fuel injection manifolds into combustion chambers

ABSTRACT

A device for securing within a combustion chamber an injection manifold which is connected to the wall of the said chamber by a pipe section preferably curved into a &#39;&#39;&#39;&#39;swan-neck,&#39;&#39;&#39;&#39; said device comprising a linkage system connected to the manifold and to a reference structure such as a stabilizer in such a way as to permit the manifold to undergo displacement parallel to itself by maintaining two points on the manifold in an axial plane of the chamber that contains the point where the pipe section passes through the said wall. The linkage system may comprise two link rods contained within this plane and pivotally mounted about axes perpendicular to the said plane, and several pairs of further link rods pivotally attached by swivel or universal joints.

iJnited States Patent 1 Camboulives et al.

[ 1 Oct. 30, 1973 FIXING OF FUEL INJECTION MANIFOLDS INTO COMBUSTION CHAMBERS Inventors: Andre Alphonse Mederic Leon Camboulives, Billancourt; Roger Alfred Jules Vandenbroucke, Antony, both of France Societe Nationale dEtude et de Construction de Moteurs dAviation, Paris, France Filed: Jan. 18, 1972 Appl. N0.: 218,811

[73] Assignee:

[30] Foreign Application Priority Data Jan. 19, I971 France 7101683 U.S. Cl. (So/39.32, (SO/39.72 R, 60/39.74 R, 60/261 Int. Cl F02c 7/20, F02c 7/22 Field of Search 60/39.3l, 39.32, 60/39.72 R, 39.74 R, 261

References Cited UNITED STATES PATENTS 9/1963 Bauger et al 60/39.72 R 3/1972 Arand (SO/39.72 R X 10/ 1962 Krabacher et al. 6O/39 'BB FOREIGN PATENTS OR APPLICATIONS 82l,286 l0/l959 Great Britain 60/39.72 R

Primary Examiner-Carlton R. Croyle Assistant Examiner-Robert E. Garrett A!t0rneyWilliam J. Daniel [57] ABSTRACT A device for securing within a combustion chamber an injection manifold which is connected to the wall of the said chamber by a pipe section preferably curved into a swan-neck," said device comprising a linkage system connected to the manifold and to a reference structure such as a stabilizer in such a way as to permit the manifold to undergo displacement parallel to itself by maintainingtwo points on the manifold in an axial plane of the chamber that contains the point where the pipe section passes through the said wall. The linkage system may comprise two link rods contained within this plane and pivotally mounted about axes perpendicular to the said plane, and several pairs of further link rods pivotally attached by swivel or universal joints.

10 Claims, 13 Drawing Figures 1 FIXING OF FUEL INJECTION MANIFOLDS INTO COMBUSTION CHAMBERS The invention relates tothe fixing of an injection manifold, which operates to inject fuel, into a space where its combustion takes place. Hereinafter such a space will be called a combustion chamber; this may more especially be a main combustion chamber or an afterburner Jet-pipe for an aircraft powerplant.

The operating cycle of a turbojet engine is greatly improved by a reheat system applied to the gases exiting from the turbine of the turbojet engine, i.e., by the combustion in the midst of these gases of fuel injected into a so-called afterburner jet-pipe. The thrust of the turbojet engine is thus increased to remarkable proportions. The fuel is injected into the afterburner jet-pipe via one or more injectors located either'upstream of a flame stabilizer or inside the said stabilizer. The injectors are generally arranged in the form of a circular manifold within the afterburner jet-pipe.

The fixing of this injection manifold presents a problem that is difficult to solve because of the high temperatures to which it is subjected in operation and which themselves give rise to major thermal expansions. The latter in their turn give rise to stresses and deformations. The deformations bring with them the risk that they will appreciably modify the respective positions of the injection manifold and of the adjacent parts, in particular the position of themanifold with reference ,to the flame stabilizer, and consequently will alter the smooth operation of the afterburner; If an attempt is made'to immobilize the injection manifold in the afterburner jet-pipe, the risk is one of bringing inadmissible stresses into play. This problem is rendered even more difficult to solve by reason of the fact that the fuel stored externally of the jet-engine must be fed to the injection manifold by piping which goes through the wall of the afterburner jet-pipe. The length of this piping included between the manifold and the jet-pipe wall must be as short as possible so as to obviate the risk of coking-up of the fuel because of the high temperature of the gases in the afterburner jet-pipe.

Problems of the same order arise as regards the fixing of an injection manifold in a combustion chamber, i.e., in a space where high-temperature combustion takes place, for example in the main combustion chamber of a jet turbine engine or of a'gas turbine.

The present invention aims to solve these problems by providing a practically isostatic suspension system for the injection manifold, this system eliminating the major stresses that are of thermal origin by permitting limited displacements of the manifold in relation to adjacent parts to which the manifold is operatively linked.

The technique is already known more especially through U.S. Pat. No. 3,102,392 to Bauger, Lacroix and Phelipon, of connecting an injection manifold to the combustion chamber by means of pivotally connected link rods.

According to the present. invention, the manifold is connected to a reference structure (positioned inside the combustion chamber) by means of a jointed linkage system: which permits the manifold to undergo displacement parallel to itself by keeping two points on the latter in a single axial plane of the said chamber, which plane contains the point where the length of feed-pipe for the manifold passes through the wall of the combustion chamber. The junction of this length of piping with the injection manifold will preferably be offset in a transverse direction with reference to the point of penetration, in such a way as not to be located in this axial plane itself. The length of piping is, for example, bent in a swan-neck shape.

In one embodiment, the linkage system comprises two link rods which connect to the reference structure the two points on the manifold respectively which are located in the said axial plane, each of the rods being pivotally connected at either end about an axis perpendicular to the said plane, and the system also comprises a plurality of pairs of link rods arranged symmetrically with reference to the said plane, these being connected by swivel or universal joints to the manifold and the reference structure. All the said rods are preferably mounted parallel to the axis of the combustion chamber. They are preferably positioned equidistantly.

The reference structure is preferably a flame stabilizer. A displacement by a few millimeters of the manifold (this being parallel to the same) with reference to the stabilizer which acts to support it does not harm the proper operation of the assembly, and introduces neither stresser nor deformations into the manifold, this being whatever the difference in temperature between the manifold and the stabilizer that brought about this relative displacement.

In one embodiment, the injection manifold itself acts as a support means for a further combustion-chamber member, for example for an annular member called an anvil, against which the manifold hurls the fuel to ensure its pulverization, the manifold being connected to the said chamber by further link rods pivotally connected to the said member and to the manifold about tangentially arranged axes.

The following description relating to the accompanying drawings and given by way of non-limitative example will bring out the advantages of the invention and the method of putting them into effect, features emerging both from the text and the figures naturally forming part of the invention. In the drawings:

FIG. 1 is a view of a diagrammatic axial section taken through an afterburner jet-pipe of an aircraft jet turbine engine;

FIG. 2 is a section on a larger scale taken along the line II'-II in FIG. 1;

FIGS. 3, 4 and 5 are sections on a still larger scale taken along the lines III-III, IVI\ and VV respectively in FIG. 2;

. FIGS. 3a, 4a and 5a are sections taken along the lines IIIa--IIIa, IVa-IVa and Va-Va respectively of FIGS. 3, 4 and 5;

FIGS. 6 and 7 are sections taken along the lines VI-VI and VIIVII respectively in FIG. 5;

FIG. 8 is a section taken along the line VIII-VIII in FIG. 2; and showing a modification;

FIG. 9 is a fractional view similar to FIG. 2, showing a further modification; and

FIG. 9a is a view obtained looking along the arrow IX in FIG. 9.'

The afterburner jet-pipe shown in FIG. 1 comprises a wall 1 of revolution about the axis X-X'. It receives a hot-gas flow coming from the turbine of an aircraft jet engine (not shown) and flowing in the direction of the arrow F The gases of said flow are reheated in the jetpipe by the combustion of fuel injected via a manifold 2, and they exit from the jet-pipe following the arrow F so as to be ejected into an exhaust nozzle (not shown). The injection manifold 2 is a circular tube coaxial with the jet-pipe and provided on its upstream face with small nozzles 2a (FIG. 2) by which it injects fuel which undergoes atomization against an annular anvil 3 positioned further upstream. The said anvil 3 has a U-shaped cross-section the branches of which are turned upstream; its shape is illustrated more clearly in FIGS. 3 and 3a. In other embodiments (not shown) the branches of the U may be turned downstream. Downstream of the injection manifold 2 there is a stabilizer ring 4 arranged which fulfils the role of a flame stabilizer. The stabilizer has a cross-section in the form of a V with a rounded apex, the branches of which are turned downstream as shown in FIGS. 3 and 3a.

The stabilizer ring 4 is attached to the wall 1 of the afterburner jet-pipe in a well-known manner by means of an arrangement of link rods of the type described and shown in the above-mentioned U.S. Pat. No. 3,102,392, one of which is fractionally illustrated at 4a in FIG. 4.

The injection manifold 2 is fed with fuel by way of piping which comprises a swan-neck section 5 (FIG. 2) which passes through the wall 1 of the afterburner jet-pipe and is connected by other lengths, including an elbow shown at 6, to a pressurized-fuel source (not shown). The section 5 communicates with the injection manifold 2 by a three-way junction 5a, and with the elbow 6 by ajunction 5b positioned in line with the wall 1, which is clamped between a sleeper nut 50 and a ro? tating nut 5d. The junction 5b has its axis arranged perpendicularly to the wall 1, and A denotes the point of intersection between the axis of the junction 5b and the neutral surface of the wall 1. The manifold 1 and the section 5 are configured so that the clamping of the wall 1 between the two nuts 50 and 5d corresponds, in the absence of any other suspension system for the manifold and when the afterburner jet-pipe is cold, to a position of the manifold which is such that it will be centred on the axis X-X and positioned in a plane perpendicular to the said axis.

The injection manifold 2 is connected to the stabilizer ring 4 by two link rods pivotally connected to the manifold about tangential axes at two respective points B and C located in an axial plane P which passes through the point A, and by four pairs of rods attached by universal joints to the manifold at points D and E, F and G, H and I, J and K, which are symmetrical with reference to the said axial plane. The two rods pivotally connected at B and C are likewise connected to the stabilizer ring 4 about tangential axes, and the other rods are likewise attached by universal joints to the stabilizer ring. All the rods are mounted parallel to the axis X-X' of the afterburner pipe. In the embodiment shown, the points B, D, F, H, J, K, I, G and E are arranged at the vertices of a nine-sided regular polygon the tenth point of attachment C, diametrically opposite the point B, is not located at a vertex of the said polygon, and is positioned at an equal distance from the two adjoining points J and K. Since the point of attachment B is located in the plane P which contains the axis XX' and the point A, the junction 5a is offset away from the said plane, to the end of the length of pipe 5 bent over like a swan-neck."

The manifold 2 comprises at C a machined sleeve 7 (FIGS. 4 and 4a) carrying a projecting yoke 7a turned downstream and, in respect of the other pivotal points of the rods, nine sleeves 8 each carrying a yoke 8a pointing downstream and a yoke 8b pointing upstream (FIGS. 3, 3a and 5, 5a). The machined sleeves 7 and 8 are joined by a welding process to bent pipe sections 9 (FIG. 2) so as to constitute the manifold 2 connected to the junction 5a.

The link rod 10 (FIGS. 3 and 3a) joining the point B of the manifold 2 to the stabilizer ring 4 is pivotally connected to the latter about a pin 10a arranged tangentially and supported by a yoke 11 welded to the stabilizer ring. The rod 10 is pivotally connected to the manifold 2 about a pin 10b likewise arranged tangentially (i.e., mounted perpendicularly to the axial plane P) and carried by the yoke 8a. The point C is similarly attached to the stabilizer ring by a rod 12 (FIGS. 4 and 4a) pivotally connected to the stabilizer ring by a pin 12a carried by a yoke 11a, and to the manifold by a pin 12b carried by the yoke 7a, the two pins 12a and 12b being also arranged tangentially to the stabilizer ring and to the manifold respectively. The branches of the yokes 11, 110, 8a and 7a are spaced apart so that the rods 10 and 12 will have a wide purchase on the stabilizer ring and on the manifold so as to retain as far as possible the parallelism of the plane of the manifold. The rods 10 and 12 form a fork at their end adjacent to the burner ring, this making it possible to arrange between the branches of this fork, in the centre of the pins 10a and 12a, rods such as those at 4a (FIG. 4) which act to secure the burner ring 4 to the wall 1. Each of the pins 10a, 10b, 12a, 12b is provided at one end with a hexagonal head 13 and at the other end with a grooved collar 14, in the groove of which is fitted a lock-pin 15 in the form ofa U which passes through the pin and the collar.

At the start of operation of the afterburner, the thermal expansion of the manifold 2 displaces respectively: point B to B point C to C and the centre 0 of the manifold to O virtually in the direction of the axis of the junction 5b and of the straight part of the pipe section 5, the slanting portion of which is as short as possible for the reason given above. The displacement of the points B and C of the manifold is therefore orthogonal to the pins 10b and 12b, so that the rods 10 and 12 pivot without deformation about the pins 10a and 12a supported by the burner ring 4. The manifold 2 will not shift appreciably in the direction of the axis X-X since the link rods 10 and 12 are, when cold, parallel to this axis. Whatever eventuates, the manifold 2 will undergo displacement parallel to itself.

The other attachment points for the manifold, i.e., the points D, E, F, G, H, I, J and K, are positioned outside the axial plane P passing through the point A. If the said points of the manifold were fixed to the stabilizer ring 4 by link rods pivotally connected about tangential axes as are'the rods 10 and 12, then stresses giving rise to deformations would occur in the manifold 2 and in its suspension system, since the displacements of the manifold parallel to itself would not at these points be orthogonal to the tangential axes of articulation. To obtain a suspension system which is in practice isostatic, each of the said points on the manifold is connected to the stabilizer ring 4 by a link rod 16 (FIGS. 5 and 5a) pivotally connected about pins 16a and 16b, themselves mounted respectively in pivoting plugs 17, 18 in such a way as to provide a swivel or universaljoint type suspension, i.e., a suspension in which each end of the rod is articulated about a point and not about an axis.

Each of the cylindrical plugs 17, 18 is traversed transversely, at a right angle to its axis, by an oblong opening 17a, 18a the width of which is adequate to receive, with a degree of play, the flattish tip 16c, 16d of the rod 16, and the length of which is sufficient to allow the travel of this rod in correspondence with the highest temperatures likely to prevail in the afterburner jet-pipe. The plug 17 is mounted in a yoke 19 similar to the yokes 11 and 11a and is welded on the stabilizer ring 4; the yoke 18 is mounted pivotally in the yoke 8a. Each of the two plugs 17 and 18 of each rod 16 therefore rotates in its respective yoke so that the pins 16a and 16b will be continuously orthogonal to the movement of the articulation point of this rod on the manifold 2, which expands because of its rise in temperature.

The annular anvil 3 has, as had already beenindicated, a U-shaped section an active pulverizing surface of which, constituted by the base of the U, forms a flat ring parallel to the mean plane of the manifold 2 which is facing it. The said flat ring is pierced, opposite each of the points C, D, E, F, G, H, I, J and K, by an opening 20 which affordspassage to a link rod 21 which is at its downstream end pivotally attached about pin 21a supported by the yoke 8b, and at its upstream end about pin 21b supported by two corner-plates 22 welded to the inner side of the anvil body 3. The pins 21a and 21b are held in place by respective traversing pins 23, which are themselves kept in place by spot welds 24 (FIGS. 6 and 7).

FIG. 8 illustrates a modification in which the junctions 8 positioned at the points .I and K are not connected by rods such as those at 16 to the stabilizer ring 4, but nevertheless support the pivotal pin 21a of a rod 21 which forms part of the rods supporting the anvil body 3. In this modification, the injection manifold 2 is therefore only connected to the stabilizer ring 4 by two rods l0, l2 and three pairs of rods 16.

In a further embodiment, the points such as those at B, CD, E, F, G, H, I, J and K may be located at ten vertices of regular polygon, the diametrically opposite points B and C being naturally located in the diametral plane P which contains the point A.

In the embodiment illustrated in FIG. 2, the points A,

B and C are aligned. However, the pipe section 5 might be offset upstream or downstream along the after-' burner jet-pipe provided that the points B and C upon assembly are positioned in the axial plane P which contains the point A.

The swan-neck pipe section might also be replaced (FIG. 9) by a section 5' bifurcated into a V, the junction where it passes through the wall Sb being a Y junction and the two branches of the section 5 being joined to the injection manifold 2 by two junctions S'a and 5's respectively, arranged symmetrically to the plane that contains the axis X-X' and the centre of junction Sb. The section 5' may also be offset upstream or downstream, as is shown in FIG. 9a.

It is self-evident that the embodiments described are of the invention.

We claim:

1. In a combustion chamber having a centerline and a casing wall containing a reference structure attached to the casing wall, a fuel injection manifold, a pipe section passing through the casing wall at a point of penetration, and a junction connecting said pipe section to said manifold to supply the same with fuel, an arrangement for fixing the fuel injection manifold within the casing wall, comprising a pair of link rods connecting said manifold to said reference structure and extending on each side of the centerline in a plane which contains the centerline and the point of penetration, means mounting both ends of each said link rod for pivotal movement about axes perpendicular to said plane, a plurality of pairs of further link rods connecting said manifold to said reference structure and arranged symmetrically about said plane, and means mounting each end of each said further link rod for swivelling movement.

2. A device as claimed in claim 1, in which the junction is offset circumferentially from said plane.

3. A device as claimed in claim 2, in which the junction is offset from a plane containing the point of penetration and perpendicular to the centerline.

4. A device as claimed in claim 1, in which the fuel injection manifold itself acts as a support means for an anvil body for fuel-pulverization and further comprising a plurality of rods connecting said body to said manifold, means mounting a first end of each said rod for pivotal movement about an axis extending tangentially to said manifold in a plane perpendicular to the centerline and means mounting a second end of each said rod for pivotal movement about an axis extending tangentially to said body in a plane perpendicular to the centerline.

5. A device-as claimed in claim 1, in which said further link rods are connected to said manifold and reference structure by swivel joints.

6. A device as claimed in claim 1, in which said further link rods are connected to said manifold and reference structure by universal joints.

7. A device as claimed in claim 1, in which said link rods are mounted parallel to the axis of the combustion chamber. i

8. A device as claimed in claim 1, in which said manifold is of circular form and the swivelling attachment points on the manifold of said further link rods form, along with one of the points of the said manifold that are located in said plane, the vertices of a regular polygon comprising an odd number of sides.

9. A device as claimed in claim 1, in which said manifold is of circular form and the swivelling attachment points on the manifold of said further link rods form, along with the two points of the said manifold that are located in saidplane, a regular polygon comprising an 'even number of sides.

10; A device as claimed in claim 1, in which the reference structure is a flame stabilizer. 

1. In a combustion chamber having a centerline and a casing wall containing a reference structure attached to the casing wall, a fuel injection manifold, a pipe section passing through the casing wall at a point of penetration, and a junction connecting said pipe section to said manifold to supply the same with fuel, an arrangement for fixing the fuel injection manifold within the casing wall, comprising a pair of link rods connecting said manifold to said reference structure and extending on each side of the centerline in a plane whIch contains the centerline and the point of penetration, means mounting both ends of each said link rod for pivotal movement about axes perpendicular to said plane, a plurality of pairs of further link rods connecting said manifold to said reference structure and arranged symmetrically about said plane, and means mounting each end of each said further link rod for swivelling movement.
 2. A device as claimed in claim 1, in which the junction is offset circumferentially from said plane.
 3. A device as claimed in claim 2, in which the junction is offset from a plane containing the point of penetration and perpendicular to the centerline.
 4. A device as claimed in claim 1, in which the fuel injection manifold itself acts as a support means for an anvil body for fuel-pulverization and further comprising a plurality of rods connecting said body to said manifold, means mounting a first end of each said rod for pivotal movement about an axis extending tangentially to said manifold in a plane perpendicular to the centerline and means mounting a second end of each said rod for pivotal movement about an axis extending tangentially to said body in a plane perpendicular to the centerline.
 5. A device as claimed in claim 1, in which said further link rods are connected to said manifold and reference structure by swivel joints.
 6. A device as claimed in claim 1, in which said further link rods are connected to said manifold and reference structure by universal joints.
 7. A device as claimed in claim 1, in which said link rods are mounted parallel to the axis of the combustion chamber.
 8. A device as claimed in claim 1, in which said manifold is of circular form and the swivelling attachment points on the manifold of said further link rods form, along with one of the points of the said manifold that are located in said plane, the vertices of a regular polygon comprising an odd number of sides.
 9. A device as claimed in claim 1, in which said manifold is of circular form and the swivelling attachment points on the manifold of said further link rods form, along with the two points of the said manifold that are located in said plane, a regular polygon comprising an even number of sides.
 10. A device as claimed in claim 1, in which the reference structure is a flame stabilizer. 